Recent years have seen a demand for a material having a greater heat-dissipation or heat-transfer property, specifically, highly oriented graphite including layers of graphite (hereinafter referred to as “graphite layers”) that are placed on top of one another in a lamination direction over a thickness of not less than 20 mm. Highly oriented graphite is graphite including highly oriented graphite layers, specifically graphite having a thermal conductivity of not less than 800 W/(m·K) in a direction in which the graphite layers are oriented.
Highly oriented graphite is produced by, for example, a method disclosed in Patent Literature 1, that is, a method of (i) placing, on top of one another, polymeric films or carbonaceous films each produced from a polymeric film and (ii) heat-treating the laminated body under pressure to a temperature of not lower than 3000° C. from a temperature region other than the temperature region of 2000° C. to 2600° C.